model.Matrix | R Documentation |
model.Matrix
creates design matrix, very much like the
standard R function model.matrix
, however returning a
dense or sparse object of class modelMatrix
.
model.Matrix(object, data = environment(object),
contrasts.arg = NULL, xlev = NULL,
sparse = FALSE, drop.unused.levels = FALSE, ...)
object |
an object of an appropriate class. For the default
method, a model formula or a |
data |
a data frame created with |
contrasts.arg |
A list, whose entries are values (numeric
matrices or character strings naming functions) to be used
as replacement values for the |
xlev |
to be used as argument of |
sparse |
logical indicating if the result should be sparse
(of class |
drop.unused.levels |
used only when |
... |
further arguments passed to or from other methods. |
model.Matrix()
is a simple wrapper either (sparse = FALSE
)
around the traditional model.matrix()
returning a
"ddenseModelMatrix"
, or (sparse = TRUE
)
around sparse.model.matrix()
, returning a
"dsparseModelMatrix"
object.
model.Matrix
creates a design matrix from the description given
in terms(object)
, using the data in data
which must
supply variables with the same names as would be created by a call to
model.frame(object)
or, more precisely, by evaluating
attr(terms(object), "variables")
.
For more details, see model.matrix
.
an object inheriting from class modelMatrix
, by
default, ddenseModelMatrix
.
model.matrix
,
sparse.model.matrix
.
data(CO2, package="datasets")
class(sm <- model.Matrix(~ 0+Type*Treatment, data=CO2, sparse=TRUE))
class(dm <- model.Matrix(~ 0+Type*Treatment, data=CO2, sparse=FALSE))
stopifnot(dim(sm) == c(84,4), dim(sm) == dim(dm), all(sm == dm))
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